Leuco compounds and process of making same.



UNITED STATES PATENT OFFICE.

ALBRECHT SCHMIDT AND ADOLF STEINDORFF, OF HGCHST-ON-THE-MAIN, GERMANY,

ASSIGNORS T0 FARBWERKE VORM. MEISTER LUCIUS & BB'lj'NING, OF HtlCHST-ON-THE-MAIN, GERMANY.

LEUCO COMPOUNDS AND PROCESS OF MAKING SAME.

No Drawing.

T all whom it may concern:

Be it known that we, ALBRECHT Sonmnrr, Ph. D., chemist, and ADoLrSTEINDORFF, Ph. D., chemist, citizens of the Empire of Germany, residingat Hochst-on-the-Main, Germany, have invented certain new and usefulImprovements .in New Leuco Conipounds and Processes of Making Same, ofwhich the following is a specification.

The vat-dyestuffs which, according to German Patents Nos. 222640, 224590and 224591, are derived from carbazol or its N- alkyl, orN-aryl-substitution products, for

instance the hydron blue G, andwhich are comprised under the collectiveterm dyestuffs of the hydron-blue series described hereinafter, are withdifliculty reduced by by the addition of hydrosulfite to the dyebath orto the stock-vat, and consume a great quantity of hydrosulfite in thepreparation of such vats. Hydronblue G is a sulfurization product ofalkyl-carbazol-indophenol, having the formula Alkyl l oj /N w k/ and thehydronblue series are sulfurization products of carbazol-indophenol andtheir alkyl-substitution products, as shown by the formulan \/W W/\' K/which represents hydronblue R, and by substitution the group N-H becomesNG H thereby forming hydronblue G. Now we have found that it isadvantageous not to prepare the leuco compounds of the said dyestuffs ofthe hydronblue series at the place where they are used, and where thereare available only comparatively weak and therefore disadvantageousreducing agents, but that it is preferable to effect the reductionduring the manufacture, for in- .stance by using highly concentratedsoluin which case also cheap reducingtions,

such as hydrosulfite-lye, or the like agents,

may be employed. We have further found Specification of Letters Patent.

Patented June 1, 1915.

' stuffs described in German Patents Nos.

222640, 224590, and 224.591 (including the leuco salts of thesedyestuffs), which compounds are produced by reduction either by means ofhydrosulfite or by another reducing agent. Suitable substances solublein water and not easily dried up, are the carbohydrates, for instancemolasses, syrup, glucose, invert-sugar, dextrin or the like. Equallygood results are obtained by using instead of the said substances-theirtechnical equivalents, for instance glycerin, Woodmolasses, that is tosay sulfite-pitch, or the like. Therefore in our present application theterm carbohydrates comprises not only the carbohydrates themselves butalso their technical equivalents. The incorporation may be effectedeither by simply mixing the said leuco compounds, or the correspondingleuco salts, with the additional substances, or by drying them uptogether with the latter, or by using as reducing agents the additionalsubstances themselves so far as.

or the like, by which the same result is obtained.

Example I: 100 parts by weight of the leuco compounds obtained from thevat-d estufi's described in German Patents os. 222640, 224590, and224591, for instance 100 parts of the leuco compound of the dyestuifobtained from nitrosophenol and methyl or ethyl carbazol, are mixed inthe form of a highly concentrated press-cake with 80 parts of molasses,treacle (syrup), glucose, glycerin or the like. The product thusobtained is fit for transport, keeps for an indefinite time and can bedirectly used for dyeing on addition of alkali and, if required, ofhydro- If for the free leuco compounds their alkali salts aresubstituted, there are directly obtained stable vats of high concentration. By evaporating them in vacuo to dryness, the products areobtained in a solid form. We have, moreover, found that theabove-described products, particularly the aste G of 20% and, if

alkaline leuco salts,

thus obtained. These products when dis-' solved in water are suitablefor dyeing, almost without the addition of hydrosulfite, and possess thetinctorial power of the primary paste after reduction with hydrosulfite.Example II: 500 grams of hydron blue strength are stirred, while eating,in presence of 150 grams of glucose and 100 grams of caustic soda lye of40 B. required, evaporated in vacuo to siccity. Thus a brown friableproduct is obtained which can be directly used for dyeing, if required,with the hydrosulfite or glucose, the addition of the latter beingpreferable for the fermentationvat or the glucose vat.

Having now described our invention, what we claim is:

1. The herein-described process of making stable concentratedpreparations of leuco compounds and their alkali salts of the dyestuffsof the hydronblue series, which consists in incorporating with saidleuco compounds bodies which do not readily dry up and are soluble inwater.

' 2. The herein-described process of making stable concentratedpreparations of leuco .compounds and their alkali salts of the dye studsof the hydron-blue series, which consists in incorporating with saidleuco compounds organic reducing agents which addition of some mamas upand are soluble in drates.

5. The herein-described process of making stable concentratedpreparations of leucocompound alkali salts ofthe dyestuffs ofithehydron-blue series, which consists in heating the dyestufi with glucoseand alkalihydrates, and evaporating to dryness.

As new products, the stable concentrated preparations of leuco compoundsand their alkali salts of the dyestuffs of the hydron-blue series, saidpreparations being soluble in water and diluted alkalis, depositing whenoxidized with air the dyestufis of the hydron-blue series, and yieldingon such oxidation and on filtration a filtrate which shows theproperties of a solution in Water of a carbohydrate heated with analkali hydrate.

In testimony whereof, we afiix our signatures in presence of twowitnesses.

ALBRECHT SCHMIDT. ADOLF STEIN DORFF. Witnesses:

JEAN Gnu-ND, CARL Grou 50 ingthe dyestufi with glucose and'alka-li hy-

